Today, endpoints implementing v2 cannot properly fallback to v1 because the underlying transport that deals with authentication (Basic / Token) doesn't get annotated.
This doesn't affect DockerHub because the DockerHub endpoint appears as 'https://index.docker.io/v1/' (in .dockercfg), and the 'v1' tricks this logic just long enough that the transport is always annotated for DockerHub accesses.
Signed-off-by: Matt Moore <mattmoor@google.com>
Upstream-commit: c2315102ff01c093750d0675c8e94aed5ed2fe46
Component: engine
9a1cbf52de